1. Field of the Invention
The present invention relates to a door lock system for a vehicle.
2. Description of the Related Art
Vehicles such as a four-wheeled vehicle generally include a door lock system between an outside handle and a latch mechanism in a side door.
The latch mechanism includes a latch and a ratchet for engagement. When the side door is closed with respect to a vehicle body, the latch receives a striker provided on the vehicle body in a locking manner, and the ratchet engages with the latch to retain the striker in the locked state so that the side door is held in a closed state with respect to the vehicle body.
The door lock system includes a base plate. A handle lever shaft, a locking lever shaft, and a ratchet lever shaft are disposed on the base plate.
A handle lever is rotatably supported on the handle lever shaft. An outside-handle connecting member is disposed on an end of the handle lever to connect the handle lever to an outside handle. A handle lever spring is interposed between the handle lever and the base plate. A resilient force of the handle lever spring brings the handle lever into contact with a stopper on the base plate, thereby defining a non-operable position of the handle lever. The handle lever is rotated from the non-operable position to an operable position in response to, for instance, a door-opening operation performed by a driver using the outside handle.
A locking lever is rotatably supported on the locking lever shaft. A lock-knob connecting member is provided on an end of the locking lever to connect the locking lever to a lock knob (locking means). The lock knob is disposed in a cabin of the vehicle. Whereas operating the lock knob to unlock the door causes the locking lever to rotate from a locked position to an unlocked position, operating the lock knob to lock the door causes the locking lever to rotate from the unlocked position to the locked position.
A ratchet lever that includes a pressure-receiving portion is rotatably supported on the ratchet lever shaft and interlocked with the ratchet. The ratchet lever disengages the ratchet from the latch when the pressure-receiving portion receives pressure.
A link lever (second link lever) is interposed between the handle lever and the locking lever for coupling therebetween. The link lever is movable in response to rotation of the handle lever, and pivotable about a coupling portion between the link lever and the handle lever in response to rotation of the locking lever. A panic lever shaft (shaft member), on which a plate-like panic lever (first link lever) is rotatably provided, is disposed on the link lever.
The panic lever extends radially outward with respect to the axis of the panic lever shaft toward the pressure-receiving portion of the ratchet lever when the locking lever is in the unlocked position. The panic lever has a pressing portion (distal end) and a protrusion, and can press the pressure-receiving portion of the ratchet lever with the pressing portion. The protrusion protrudes from the plate-like front face of the panic lever. A notch for receiving a portion of the link lever is defined in the protrusion. When an unlocking operation is performed and the locking lever is moved from the locked position to the unlocked position, the panic lever is moved to a facing position (transmitting position) at which the pressing portion of the panic lever faces the pressure-receiving portion of the ratchet lever. On the other hand, when a locking operation is performed and the locking lever is moved from the unlocked position to the locked position, the pressing portion of the panic lever moves to a non-facing position (non-transmitting position) out of the transmitting position.
A panic spring (urging means) is interposed between the link lever and the panic lever. The panic spring constantly urges the first link lever toward the facing position.
The link lever is partially inserted into the notch in the panic lever, and the resilient force of the panic spring brings a side end of the link lever into contact with a deep end of the notch, thereby defining the facing position of the panic lever. Thus, the protrusion functions as a stopper that defines the facing position of the panic lever relative to the link lever. When the panic lever is at the facing position, the pressing portion is near a distal end of the link lever.
The door lock system operates such that, when the outside handle is operated in a direction to open the door with the handle lever moved to assume the non-operable position, the locking lever moved to assume the unlocked position, and the panic lever moved to assume the facing position (hereinafter, “unlocked state”), the link lever is moved via the handle lever in response to the door-opening operation such that the pressure-receiving portion of the ratchet lever comes into contact with the pressing portion of the panic lever. The movement of the link lever in turn causes the pressing portion of the panic lever to press the pressure-receiving portion of the ratchet lever, thereby disengaging the latch from the ratchet. Accordingly, even when the side door is closed, the side door can be moved and opened by pulling the outside handle outward of the vehicle.
The door lock system operates such that, when the outside handle is operated in the direction to open the door with the handle lever moved to assume the non-operable position, the locking lever moved to assume the locked position, and the panic lever moved to assume the non-facing position (hereinafter, “locked state”), the link lever is moved through the handle lever in response to the door-opening operation. During this movement, only the link lever and the panic lever are moved, and the pressing portion of the panic lever does not press the pressure-receiving portion of the ratchet lever. Thus, even when the outside handle is operated in the direction to open the door, the ratchet remains to be engaged by the latch. This means that when the side door is in the closed state, the side door cannot be moved and opened by pulling the outside handle outward of the vehicle.
Unlocking the locked door using the lock knob while the outside handle is operated in the direction to open the door in the locked state will be described below.
When the door-opening operation using the outside handle is performed prior to the unlocking operation, only the link lever and the panic lever are moved without bringing the pressing portion of the panic lever into contact with the pressure-receiving portion of the ratchet lever. When the unlocking operation using the lock knob is performed in this state, the locking lever is rotated from the locked position to the unlocked position. The rotation of the locking lever causes the link lever to swing about the coupling portion between the handle lever and the link lever. At this time, the panic lever is stopped because the pressing portion of the panic lever is caught by the pressure-receiving portion of the ratchet lever. Thus, the pressing portion of the panic lever is positioned away from the distal end of the link lever in the axial direction of the panic lever shaft.
Thereafter, when the door-opening operation using the outside handle is stopped to cause the handle lever rotated from the operable position to the non-operable position, the resilient force of the panic spring rotates the panic lever to bring the pressing portion into proximity of the distal end of the link lever in a radially outward direction with respect to the shaft member. The rotation of the panic lever is stopped when the link lever is partially inserted into the notch in the panic lever and the resilient force of the panic spring brings the side end of the link lever into contact with the deep end of the notch. Hence, the panic lever is located at the facing position, thereby bringing the door lock system into the unlocked state.
When the door-opening operation using the outside handle is performed again in this state, the ratchet is successfully disengaged from the latch, thereby allowing the side door to be moved and opened. Thus, according to the door lock system, when the unlocking operation using the lock knob is performed in the locked state in conjunction with the door-opening operation using the outside handle, the need of operating the lock knob twice to unlock the door is eliminated, thereby reducing the number of operations (for example, see Japanese Patent No. 3574990).
The door lock system is disadvantageous in that, in the course of the panic lever's moving between the position at which the pressing portion is away from the distal end of the link lever in the radially outward direction with respect to the panic lever shaft and the position at which the pressing portion is near the distal end of the link lever in the same direction, the pressing portion of the panic lever can be moved in the axial direction of the panic lever shaft. This can result in a change of a positional relationship between the pressing portion of the panic lever and the distal end of the link lever in the axial direction of the panic lever shaft. If the pressing portion is away from the distal end of the link lever in the axial direction of the panic lever shaft, the link lever is not inserted into the notch in the panic lever, and the side end of the link lever is not brought into contact with the deep end of the notch. Hence, the panic lever undesirably fails to return to the facing position.
When the door-opening operation is performed on the door lock system in the unlocked state with the panic lever not returned to the facing position, it is possible that the pressing portion of the panic lever fails to press the pressing portion of the ratchet lever, which leads to a failure in moving and opening the side door.